Conference Coverage

CO2 laser guided by confocal microscopy effectively treated superficial BCC


 

REPORTING FROM ASLMS 2018

– The use of CO2 laser ablation guided by reflectance confocal microscopy is an effective, minimally invasive treatment for superficial and early nodular basal cell carcinoma (BCC), according to results from an ongoing study.

“While surgery is the gold standard for many basal cell carcinomas, nonsurgical therapies may be a good option for the superficial and early nodular subtypes,” lead study author Anthony M. Rossi, MD, said at the annual conference of the American Society for Laser Medicine and Surgery. “Laser ablation was used many years ago, so this is not a novel concept, but we’re bringing it back and we’re trying to use confocal microscopy to hone in on the basal cell and selectively target the tumor.”

Dr. Anthony M. Rossi, dermatology service, Memorial Sloan Kettering Cancer Center, New York Courtesy MSKCC

Dr. Anthony Rossi

Reflectance confocal microscopy (RCM) is a noninvasive imaging modality that provides real-time, cellular-level resolution images. “It can rapidly assess the skin in the x-y plane as well as up to about 200 mcm in depth,” said Dr. Rossi of the dermatology service at Memorial Sloan Kettering Cancer Center, New York. “There are characteristic features of these basal cells, including nuclei streaming and tumor islands.”

For the current analysis, he and his associates used a 10,600 nm CO2 laser that selectively targets water to treat 20 BCCs in four males and three females with a mean age of 55 years. Of the 20 lesions, 18 were located on the limbs and trunk, while two were on the head and neck. The median lesion diameter was 7 mm. Prior to laser ablation, the researchers performed reflectance confocal microscopy to define lateral and deep margins and define the laser parameters.

A basal cell carcinoma just above a patient's ankle, prior to confocal microscopy-guided laser treatment. Courtesy Dr. Anthony M. Rossi

A basal cell carcinoma just above a patient's ankle, prior to confocal microscopy-guided laser treatment.

“We’re using dermoscopy, visual inspection, and confocal microscopy to image the biopsy site,” Dr. Rossi explained. “Using where we hone in on tumor margins, we can use the CO2 laser to ablate the tissue. We use aluminum chloride as a contrast agent, which can enhance cellular detail under RCM, similar to a process of acetowhitening. If we see a positive margin or a positive area, we go back and ablate again with the CO2 laser.”

The median number of laser passes was three, and ranged from two to eight, delivered at a fluence of 7.5 J/cm2. Reflectance confocal microscopy was repeated immediately after the laser treatment to the skin wound margins and deep margins, and it was performed every 3-6 months thereafter. “If you do confocal microscopy too early, you’ll see mainly inflammation and you may see residual tumor that hasn’t been fully resolved yet,” Dr. Rossi said.

This confocal microscopy mosaic shows discrete tumor islands representative of the basal cell carcinoma preablation. Courtesy Dr. Anthony M. Rossi

This confocal microscopy mosaic shows discrete tumor islands representative of the basal cell carcinoma preablation.

To date, the average follow-up has been 17 months, with the longest being 4 years. No recurrence has been detected clinically, dermoscopically, or by reflectance confocal microscopy. All sites show good cosmetic outcomes, he said, and reflectance confocal microscopy shows dermal features of scar. “What we’re getting better at is honing in on the features of not only basal cell tumor islands, but [also] normal structures that can be deceiving, such as hair follicles,” Dr. Rossi said. “We can see up to a depth of about 200 mcm, but when you’re in that wound with confocal microscopy, you can try to go slightly deeper. The depth of imaging is a limiting factor.”

As for future directions, he and his colleagues are developing contrast agents to enhance the ability to detect BCC tumors in vivo, to highlight tumor islands, and to differentiate sebaceous glands and hair follicles. Dr. Rossi reported having no relevant disclosures.

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